The present invention relates to an apparatus which applies coating material to an object, and more specifically, to a spray gun which directs a flow of the electrostatically charged coating material toward the object.
Known spray guns have previously been used to direct coating material toward an object. One known spray gun for directing a flow of coating material toward an object is constructed in accordance with U.S. Pat. No. 5,056,720 issued Oct. 15, 1991. Although a spray gun constructed in accordance with the aforementioned patent is satisfactory in its construction and mode of operation, it is desirable to simplify the construction of the spray gun, increase operator comfort during use of the spray gun, and increase the ability of the spray gun to apply a uniform coating of material to an object.
An improved apparatus for use in applying coating material to an object includes a spray gun having a handle portion and an extension portion which extends from the handle portion. A nozzle is connected with the extension portion to direct a flow of coating material toward the object. A coating material flow control member is disposed on the handle portion of the spray gun to control the flow of coating material. An electrode may be provided adjacent to the nozzle to electrostatically charge the coating material.
In accordance with one of the features of the present invention, an air flow control member is also disposed on the handle portion. The air flow control member is is manually operable to direct a flow of air through coating material passages and through the nozzle to remove excess coating material from the passages and/or nozzle.
In accordance with another feature of the invention, a membrane switch assembly is actuated upon manual actuation of one of the flow control members. The membrane switch assembly includes a switch element which is disposed between layers of electrically insulating material. Upon manual actuation of a flow control member, the switch element is deflected to initiate a control function.
In accordance with another feature of the invention, hand grips of different sizes may be utilized with the handle portion of the spray gun. The hand grips of different sizes enable the spray gun to be adapted for manual engagement by operators having hands of different sizes. Each of the hand grips may be formed of an electrically conductive material and, when connected with the handle portion of the spray gun, is connected with an electrical ground.
In accordance with another feature of the invention, passages in the handle and/or extension portions of the spray gun are formed by cooperation between an outer wall of the spray gun and an inner wall structure. The inner wall structure may be, at least partially, formed as one piece with the outer wall of the spray gun. The inner wall structure may advantageously be utilized to form one or more passages which may receive purge air, electrode wash air, or electrical conductors.
In accordance with another feature of the invention, a voltage multiplier unit is cooled by a flow of air. To promote a transfer of heat from the voltage multiplier unit to the air, a portion of an outer surface area on the voltage multiplier unit is exposed to the flow of air through a passage in the spray gun. The voltage multiplier unit is advantageously positioned to balance the spray gun.
It should be understood that the foregoing features may be used either separately or in various combinations to provide an improved spray gun. The spray gun may be utilized to direct electrostatically charged coating materials or other coating materials toward an object. The coating materials may be liquids or solids (powder).